long count() returns the count of elements in the stream. This is a special case of a reduction (A reduction operation takes a sequence of input elements and combines them into a single summary result by repeated application of a combining operation). This is a terminal operation i.e, it may traverse the stream to produce a result or a side-effect. After the terminal operation is performed, the stream pipeline is considered consumed, and can no longer be used.
Syntax :
long count()
Note : The return value of count operation is the count of elements in the stream.
Example 1 : Counting number of elements in array.
// Java code for Stream.count()// to count the elements in the stream.import java.util.*;  class GFG {      // Driver code    public static void main(String[] args)    {          // creating a list of Integers        List<Integer> list = Arrays.asList(0, 2, 4, 6,                                           8, 10, 12);          // Using count() to count the number        // of elements in the stream and        // storing the result in a variable.        long total = list.stream().count();          // Displaying the number of elements        System.out.println(total);    }} |
Output :
7
Example 2 : Count number of distinct elements in a list.
// Java code for Stream.count()// to count the number of distinct// elements in the stream.import java.util.*;  class GFG {      // Driver code    public static void main(String[] args)    {          // creating a list of Strings        List<String> list = Arrays.asList("GFG", "Geeks", "for", "Geeks",                                          "Lazyroar", "GFG");          // Using count() to count the number        // of distinct elements in the stream and        // storing the result in a variable.        long total = list.stream().distinct().count();          // Displaying the number of elements        System.out.println(total);    }} |
Output :
4
